In QB desktop I could add a signature that would print on all checks that I printed. Can that be done in QB online?

Sadly, it can't be done in QBO.  

Hello there, jgradek & Just_me.

I understand how beneficial it is for you and your business to be able to add a signature to your printed checks. 

QuickBooks Online allows integration with several third-party apps. You may consider looking for an app that lets you do this in QBO. 

To search for apps through QuickBooks, here's how:

1. On the left navigation bar, select Apps.
2. Go to the Find Apps tab.
3. Use the search bar to find apps.

Also, QuickBooks Online offers various video tutorials about its functionalities that will surely help you. You may check those videos out through these links:

• Video tutorials for QuickBooks Online.
• QuickBooks Help.

Let me know if there's anything else I can help you with. Keep safe!